- Kai Germaschewski: ISDN update (including Makefiles)

[davej-history.git] / drivers / scsi / scsi_scan.c

/*
 *  scsi_scan.c Copyright (C) 2000 Eric Youngdale
 *
 *  Bus scan logic.
 *
 *  This used to live in scsi.c, but that file was just a laundry basket
 *  full of misc stuff.  This got separated out in order to make things
 *  clearer.
 */

#define __NO_VERSION__
#include <linux/config.h>
#include <linux/module.h>
#include <linux/init.h>

#include <linux/blk.h>

#include "scsi.h"
#include "hosts.h"
#include "constants.h"

#ifdef CONFIG_KMOD
#include <linux/kmod.h>
#endif

/* The following devices are known not to tolerate a lun != 0 scan for
 * one reason or another.  Some will respond to all luns, others will
 * lock up.
 */

#define BLIST_NOLUN             0x001
#define BLIST_FORCELUN          0x002
#define BLIST_BORKEN            0x004
#define BLIST_KEY               0x008
#define BLIST_SINGLELUN         0x010
#define BLIST_NOTQ              0x020
#define BLIST_SPARSELUN         0x040
#define BLIST_MAX5LUN           0x080
#define BLIST_ISDISK            0x100
#define BLIST_ISROM             0x200

static void print_inquiry(unsigned char *data);
static int scan_scsis_single(int channel, int dev, int lun, int *max_scsi_dev,
                int *sparse_lun, Scsi_Device ** SDpnt,
                             struct Scsi_Host *shpnt, char *scsi_result);

struct dev_info {
        const char *vendor;
        const char *model;
        const char *revision;   /* Latest revision known to be bad.  Not used yet */
        unsigned flags;
};

/*
 * This is what was previously known as the blacklist.  The concept
 * has been expanded so that we can specify other types of things we
 * need to be aware of.
 */
static struct dev_info device_list[] =
{
        {"Aashima", "IMAGERY 2400SP", "1.03", BLIST_NOLUN},     /* Locks up if polled for lun != 0 */
        {"CHINON", "CD-ROM CDS-431", "H42", BLIST_NOLUN},       /* Locks up if polled for lun != 0 */
        {"CHINON", "CD-ROM CDS-535", "Q14", BLIST_NOLUN},       /* Locks up if polled for lun != 0 */
        {"DENON", "DRD-25X", "V", BLIST_NOLUN},                 /* Locks up if probed for lun != 0 */
        {"HITACHI", "DK312C", "CM81", BLIST_NOLUN},             /* Responds to all lun - dtg */
        {"HITACHI", "DK314C", "CR21", BLIST_NOLUN},             /* responds to all lun */
        {"IMS", "CDD521/10", "2.06", BLIST_NOLUN},              /* Locks-up when LUN>0 polled. */
        {"MAXTOR", "XT-3280", "PR02", BLIST_NOLUN},             /* Locks-up when LUN>0 polled. */
        {"MAXTOR", "XT-4380S", "B3C", BLIST_NOLUN},             /* Locks-up when LUN>0 polled. */
        {"MAXTOR", "MXT-1240S", "I1.2", BLIST_NOLUN},           /* Locks up when LUN>0 polled */
        {"MAXTOR", "XT-4170S", "B5A", BLIST_NOLUN},             /* Locks-up sometimes when LUN>0 polled. */
        {"MAXTOR", "XT-8760S", "B7B", BLIST_NOLUN},             /* guess what? */
        {"MEDIAVIS", "RENO CD-ROMX2A", "2.03", BLIST_NOLUN},    /*Responds to all lun */
        {"MICROP", "4110", "*", BLIST_NOTQ},                    /* Buggy Tagged Queuing */
        {"NEC", "CD-ROM DRIVE:841", "1.0", BLIST_NOLUN},        /* Locks-up when LUN>0 polled. */
        {"PHILIPS", "PCA80SC", "V4-2", BLIST_NOLUN},            /* Responds to all lun */
        {"RODIME", "RO3000S", "2.33", BLIST_NOLUN},             /* Locks up if polled for lun != 0 */
        {"SANYO", "CRD-250S", "1.20", BLIST_NOLUN},             /* causes failed REQUEST SENSE on lun 1
                                                                 * for aha152x controller, which causes
                                                                 * SCSI code to reset bus.*/
        {"SEAGATE", "ST157N", "\004|j", BLIST_NOLUN},           /* causes failed REQUEST SENSE on lun 1
                                                                 * for aha152x controller, which causes
                                                                 * SCSI code to reset bus.*/
        {"SEAGATE", "ST296", "921", BLIST_NOLUN},               /* Responds to all lun */
        {"SEAGATE", "ST1581", "6538", BLIST_NOLUN},             /* Responds to all lun */
        {"SONY", "CD-ROM CDU-541", "4.3d", BLIST_NOLUN},        
        {"SONY", "CD-ROM CDU-55S", "1.0i", BLIST_NOLUN},
        {"SONY", "CD-ROM CDU-561", "1.7x", BLIST_NOLUN},
        {"SONY", "CD-ROM CDU-8012", "*", BLIST_NOLUN},
        {"TANDBERG", "TDC 3600", "U07", BLIST_NOLUN},           /* Locks up if polled for lun != 0 */
        {"TEAC", "CD-R55S", "1.0H", BLIST_NOLUN},               /* Locks up if polled for lun != 0 */
        {"TEAC", "CD-ROM", "1.06", BLIST_NOLUN},                /* causes failed REQUEST SENSE on lun 1
                                                                 * for seagate controller, which causes
                                                                 * SCSI code to reset bus.*/
        {"TEAC", "MT-2ST/45S2-27", "RV M", BLIST_NOLUN},        /* Responds to all lun */
        {"TEXEL", "CD-ROM", "1.06", BLIST_NOLUN},               /* causes failed REQUEST SENSE on lun 1
                                                                 * for seagate controller, which causes
                                                                 * SCSI code to reset bus.*/
        {"QUANTUM", "LPS525S", "3110", BLIST_NOLUN},            /* Locks sometimes if polled for lun != 0 */
        {"QUANTUM", "PD1225S", "3110", BLIST_NOLUN},            /* Locks sometimes if polled for lun != 0 */
        {"QUANTUM", "FIREBALL ST4.3S", "0F0C", BLIST_NOLUN},    /* Locks up when polled for lun != 0 */
        {"MEDIAVIS", "CDR-H93MV", "1.31", BLIST_NOLUN},         /* Locks up if polled for lun != 0 */
        {"SANKYO", "CP525", "6.64", BLIST_NOLUN},               /* causes failed REQ SENSE, extra reset */
        {"HP", "C1750A", "3226", BLIST_NOLUN},                  /* scanjet iic */
        {"HP", "C1790A", "", BLIST_NOLUN},                      /* scanjet iip */
        {"HP", "C2500A", "", BLIST_NOLUN},                      /* scanjet iicx */
        {"YAMAHA", "CDR100", "1.00", BLIST_NOLUN},              /* Locks up if polled for lun != 0 */
        {"YAMAHA", "CDR102", "1.00", BLIST_NOLUN},              /* Locks up if polled for lun != 0  
                                                                 * extra reset */
        {"YAMAHA", "CRW8424S", "1.0", BLIST_NOLUN},             /* Locks up if polled for lun != 0 */
        {"YAMAHA", "CRW6416S", "1.0c", BLIST_NOLUN},            /* Locks up if polled for lun != 0 */
        {"MITSUMI", "CD-R CR-2201CS", "6119", BLIST_NOLUN},     /* Locks up if polled for lun != 0 */
        {"RELISYS", "Scorpio", "*", BLIST_NOLUN},               /* responds to all LUN */
        {"MICROTEK", "ScanMaker II", "5.61", BLIST_NOLUN},      /* responds to all LUN */

/*
 * Other types of devices that have special flags.
 */
        {"SONY", "CD-ROM CDU-8001", "*", BLIST_BORKEN},
        {"TEXEL", "CD-ROM", "1.06", BLIST_BORKEN},
        {"IOMEGA", "Io20S         *F", "*", BLIST_KEY},
        {"INSITE", "Floptical   F*8I", "*", BLIST_KEY},
        {"INSITE", "I325VM", "*", BLIST_KEY},
        {"LASOUND","CDX7405","3.10", BLIST_MAX5LUN | BLIST_SINGLELUN},
        {"NRC", "MBR-7", "*", BLIST_FORCELUN | BLIST_SINGLELUN},
        {"NRC", "MBR-7.4", "*", BLIST_FORCELUN | BLIST_SINGLELUN},
        {"REGAL", "CDC-4X", "*", BLIST_MAX5LUN | BLIST_SINGLELUN},
        {"NAKAMICH", "MJ-4.8S", "*", BLIST_FORCELUN | BLIST_SINGLELUN},
        {"NAKAMICH", "MJ-5.16S", "*", BLIST_FORCELUN | BLIST_SINGLELUN},
        {"PIONEER", "CD-ROM DRM-600", "*", BLIST_FORCELUN | BLIST_SINGLELUN},
        {"PIONEER", "CD-ROM DRM-602X", "*", BLIST_FORCELUN | BLIST_SINGLELUN},
        {"PIONEER", "CD-ROM DRM-604X", "*", BLIST_FORCELUN | BLIST_SINGLELUN},
        {"EMULEX", "MD21/S2     ESDI", "*", BLIST_SINGLELUN},
        {"CANON", "IPUBJD", "*", BLIST_SPARSELUN},
        {"nCipher", "Fastness Crypto", "*", BLIST_FORCELUN},
        {"DEC","HSG80","*", BLIST_FORCELUN},
        {"COMPAQ","LOGICAL VOLUME","*", BLIST_FORCELUN},
        {"NEC", "PD-1 ODX654P", "*", BLIST_FORCELUN | BLIST_SINGLELUN},
        {"MATSHITA", "PD-1", "*", BLIST_FORCELUN | BLIST_SINGLELUN},
        {"iomega", "jaz 1GB", "J.86", BLIST_NOTQ | BLIST_NOLUN},
        {"TOSHIBA","CDROM","*", BLIST_ISROM},
        {"MegaRAID", "LD", "*", BLIST_FORCELUN},
        {"DGC",  "RAID",      "*", BLIST_SPARSELUN}, // Dell PV 650F (tgt @ LUN 0)
        {"DGC",  "DISK",      "*", BLIST_SPARSELUN}, // Dell PV 650F (no tgt @ LUN 0) 
        {"DELL", "PV530F",    "*", BLIST_SPARSELUN}, // Dell PV 530F
        {"SONY", "TSL",       "*", BLIST_FORCELUN},  // DDS3 & DDS4 autoloaders
        {"DELL", "PERCRAID", "*", BLIST_FORCELUN},
        {"HP", "NetRAID-4M", "*", BLIST_FORCELUN},

        /*
         * Must be at end of list...
         */
        {NULL, NULL, NULL}
};

#ifdef CONFIG_SCSI_MULTI_LUN
static int max_scsi_luns = 8;
#else
static int max_scsi_luns = 1;
#endif

#ifdef MODULE

MODULE_PARM(max_scsi_luns, "i");
MODULE_PARM_DESC(max_scsi_luns, "last scsi LUN (should be between 1 and 8)");

#else

static int __init scsi_luns_setup(char *str)
{
        int tmp;

        if (get_option(&str, &tmp) == 1) {
                max_scsi_luns = tmp;
                return 1;
        } else {
                printk("scsi_luns_setup : usage max_scsi_luns=n "
                       "(n should be between 1 and 8)\n");
                return 0;
        }
}

__setup("max_scsi_luns=", scsi_luns_setup);

#endif

static void print_inquiry(unsigned char *data)
{
        int i;

        printk("  Vendor: ");
        for (i = 8; i < 16; i++) {
                if (data[i] >= 0x20 && i < data[4] + 5)
                        printk("%c", data[i]);
                else
                        printk(" ");
        }

        printk("  Model: ");
        for (i = 16; i < 32; i++) {
                if (data[i] >= 0x20 && i < data[4] + 5)
                        printk("%c", data[i]);
                else
                        printk(" ");
        }

        printk("  Rev: ");
        for (i = 32; i < 36; i++) {
                if (data[i] >= 0x20 && i < data[4] + 5)
                        printk("%c", data[i]);
                else
                        printk(" ");
        }

        printk("\n");

        i = data[0] & 0x1f;

        printk("  Type:   %s ",
               i < MAX_SCSI_DEVICE_CODE ? scsi_device_types[i] : "Unknown          ");
        printk("                 ANSI SCSI revision: %02x", data[2] & 0x07);
        if ((data[2] & 0x07) == 1 && (data[3] & 0x0f) == 1)
                printk(" CCS\n");
        else
                printk("\n");
}

static int get_device_flags(unsigned char *response_data)
{
        int i = 0;
        unsigned char *pnt;
        for (i = 0; 1; i++) {
                if (device_list[i].vendor == NULL)
                        return 0;
                pnt = &response_data[8];
                while (*pnt && *pnt == ' ')
                        pnt++;
                if (memcmp(device_list[i].vendor, pnt,
                           strlen(device_list[i].vendor)))
                        continue;
                pnt = &response_data[16];
                while (*pnt && *pnt == ' ')
                        pnt++;
                if (memcmp(device_list[i].model, pnt,
                           strlen(device_list[i].model)))
                        continue;
                return device_list[i].flags;
        }
        return 0;
}

/*
 *  Detecting SCSI devices :
 *  We scan all present host adapter's busses,  from ID 0 to ID (max_id).
 *  We use the INQUIRY command, determine device type, and pass the ID /
 *  lun address of all sequential devices to the tape driver, all random
 *  devices to the disk driver.
 */
void scan_scsis(struct Scsi_Host *shpnt,
                       uint hardcoded,
                       uint hchannel,
                       uint hid,
                       uint hlun)
{
        uint channel;
        int dev;
        int lun;
        int max_dev_lun;
        unsigned char *scsi_result;
        unsigned char scsi_result0[256];
        Scsi_Device *SDpnt;
        Scsi_Device *SDtail;
        int sparse_lun;

        scsi_result = NULL;

        SDpnt = (Scsi_Device *) kmalloc(sizeof(Scsi_Device),
                                        GFP_ATOMIC);
        if (SDpnt) {
                memset(SDpnt, 0, sizeof(Scsi_Device));
                /*
                 * Register the queue for the device.  All I/O requests will
                 * come in through here.  We also need to register a pointer to
                 * ourselves, since the queue handler won't know what device
                 * the queue actually represents.   We could look it up, but it
                 * is pointless work.
                 */
                scsi_initialize_queue(SDpnt, shpnt);
                SDpnt->request_queue.queuedata = (void *) SDpnt;
                /* Make sure we have something that is valid for DMA purposes */
                scsi_result = ((!shpnt->unchecked_isa_dma)
                               ? &scsi_result0[0] : kmalloc(512, GFP_DMA));
        }

        if (scsi_result == NULL) {
                printk("Unable to obtain scsi_result buffer\n");
                goto leave;
        }
        /*
         * We must chain ourself in the host_queue, so commands can time out 
         */
        SDpnt->queue_depth = 1;
        SDpnt->host = shpnt;
        SDpnt->online = TRUE;

        initialize_merge_fn(SDpnt);

        /*
         * Initialize the object that we will use to wait for command blocks.
         */
        init_waitqueue_head(&SDpnt->scpnt_wait);

        /*
         * Next, hook the device to the host in question.
         */
        SDpnt->prev = NULL;
        SDpnt->next = NULL;
        if (shpnt->host_queue != NULL) {
                SDtail = shpnt->host_queue;
                while (SDtail->next != NULL)
                        SDtail = SDtail->next;

                SDtail->next = SDpnt;
                SDpnt->prev = SDtail;
        } else {
                shpnt->host_queue = SDpnt;
        }

        /*
         * We need to increment the counter for this one device so we can track when
         * things are quiet.
         */
        if (hardcoded == 1) {
                Scsi_Device *oldSDpnt = SDpnt;
                struct Scsi_Device_Template *sdtpnt;
                channel = hchannel;
                if (channel > shpnt->max_channel)
                        goto leave;
                dev = hid;
                if (dev >= shpnt->max_id)
                        goto leave;
                lun = hlun;
                if (lun >= shpnt->max_lun)
                        goto leave;
                scan_scsis_single(channel, dev, lun, &max_dev_lun, &sparse_lun,
                                  &SDpnt, shpnt, scsi_result);
                if (SDpnt != oldSDpnt) {

                        /* it could happen the blockdevice hasn't yet been inited */
                        /* queue_depth() moved from scsi_proc_info() so that
                           it is called before scsi_build_commandblocks() */
                        if (shpnt->select_queue_depths != NULL)
                                (shpnt->select_queue_depths)(shpnt,
                                                             shpnt->host_queue);

                        for (sdtpnt = scsi_devicelist; sdtpnt; sdtpnt = sdtpnt->next)
                                if (sdtpnt->init && sdtpnt->dev_noticed)
                                        (*sdtpnt->init) ();

                        for (sdtpnt = scsi_devicelist; sdtpnt; sdtpnt = sdtpnt->next) {
                                if (sdtpnt->attach) {
                                        (*sdtpnt->attach) (oldSDpnt);
                                        if (oldSDpnt->attached) {
                                                scsi_build_commandblocks(oldSDpnt);
                                                if (0 == oldSDpnt->has_cmdblocks) {
                                                        printk("scan_scsis: DANGER, no command blocks\n");
                                                        /* What to do now ?? */
                                                }
                                        }
                                }
                        }
                        scsi_resize_dma_pool();

                        for (sdtpnt = scsi_devicelist; sdtpnt; sdtpnt = sdtpnt->next) {
                                if (sdtpnt->finish && sdtpnt->nr_dev) {
                                        (*sdtpnt->finish) ();
                                }
                        }
                }
        } else {
                /* Actual LUN. PC ordering is 0->n IBM/spec ordering is n->0 */
                int order_dev;

                for (channel = 0; channel <= shpnt->max_channel; channel++) {
                        for (dev = 0; dev < shpnt->max_id; ++dev) {
                                if (shpnt->reverse_ordering)
                                        /* Shift to scanning 15,14,13... or 7,6,5,4, */
                                        order_dev = shpnt->max_id - dev - 1;
                                else
                                        order_dev = dev;

                                if (shpnt->this_id != order_dev) {

                                        /*
                                         * We need the for so our continue, etc. work fine. We put this in
                                         * a variable so that we can override it during the scan if we
                                         * detect a device *KNOWN* to have multiple logical units.
                                         */
                                        max_dev_lun = (max_scsi_luns < shpnt->max_lun ?
                                         max_scsi_luns : shpnt->max_lun);
                                        sparse_lun = 0;
                                        for (lun = 0; lun < max_dev_lun; ++lun) {
                                                if (!scan_scsis_single(channel, order_dev, lun, &max_dev_lun,
                                                                       &sparse_lun, &SDpnt, shpnt,
                                                             scsi_result)
                                                    && !sparse_lun)
                                                        break;  /* break means don't probe further for luns!=0 */
                                        }       /* for lun ends */
                                }       /* if this_id != id ends */
                        }       /* for dev ends */
                }               /* for channel ends */
        }                       /* if/else hardcoded */

      leave:

        {                       /* Unchain SRpnt from host_queue */
                Scsi_Device *prev, *next;
                Scsi_Device *dqptr;

                for (dqptr = shpnt->host_queue; dqptr != SDpnt; dqptr = dqptr->next)
                        continue;
                if (dqptr) {
                        prev = dqptr->prev;
                        next = dqptr->next;
                        if (prev)
                                prev->next = next;
                        else
                                shpnt->host_queue = next;
                        if (next)
                                next->prev = prev;
                }
        }

        /* Last device block does not exist.  Free memory. */
        if (SDpnt != NULL) {
                blk_cleanup_queue(&SDpnt->request_queue);
                kfree((char *) SDpnt);
        }

        /* If we allocated a buffer so we could do DMA, free it now */
        if (scsi_result != &scsi_result0[0] && scsi_result != NULL) {
                kfree(scsi_result);
        } {
                Scsi_Device *sdev;
                Scsi_Cmnd *scmd;

                SCSI_LOG_SCAN_BUS(4, printk("Host status for host %p:\n", shpnt));
                for (sdev = shpnt->host_queue; sdev; sdev = sdev->next) {
                        SCSI_LOG_SCAN_BUS(4, printk("Device %d %p: ", sdev->id, sdev));
                        for (scmd = sdev->device_queue; scmd; scmd = scmd->next) {
                                SCSI_LOG_SCAN_BUS(4, printk("%p ", scmd));
                        }
                        SCSI_LOG_SCAN_BUS(4, printk("\n"));
                }
        }
}

/*
 * The worker for scan_scsis.
 * Returning 0 means Please don't ask further for lun!=0, 1 means OK go on.
 * Global variables used : scsi_devices(linked list)
 */
static int scan_scsis_single(int channel, int dev, int lun, int *max_dev_lun,
               int *sparse_lun, Scsi_Device ** SDpnt2, 
                      struct Scsi_Host *shpnt, char *scsi_result)
{
        char devname[64];
        unsigned char scsi_cmd[MAX_COMMAND_SIZE];
        struct Scsi_Device_Template *sdtpnt;
        Scsi_Device *SDtail, *SDpnt = *SDpnt2;
        Scsi_Request * SRpnt;
        int bflags, type = -1;
        extern devfs_handle_t scsi_devfs_handle;

        SDpnt->host = shpnt;
        SDpnt->id = dev;
        SDpnt->lun = lun;
        SDpnt->channel = channel;
        SDpnt->online = TRUE;

        scsi_build_commandblocks(SDpnt);
 
        /* Some low level driver could use device->type (DB) */
        SDpnt->type = -1;

        /*
         * Assume that the device will have handshaking problems, and then fix this
         * field later if it turns out it doesn't
         */
        SDpnt->borken = 1;
        SDpnt->was_reset = 0;
        SDpnt->expecting_cc_ua = 0;
        SDpnt->starved = 0;

        SRpnt = scsi_allocate_request(SDpnt);

        /*
         * We used to do a TEST_UNIT_READY before the INQUIRY but that was 
         * not really necessary.  Spec recommends using INQUIRY to scan for
         * devices (and TEST_UNIT_READY to poll for media change). - Paul G.
         */

        SCSI_LOG_SCAN_BUS(3, printk("scsi: performing INQUIRY\n"));
        /*
         * Build an INQUIRY command block.
         */
        scsi_cmd[0] = INQUIRY;
        scsi_cmd[1] = (lun << 5) & 0xe0;
        scsi_cmd[2] = 0;
        scsi_cmd[3] = 0;
        scsi_cmd[4] = 255;
        scsi_cmd[5] = 0;
        SRpnt->sr_cmd_len = 0;
        SRpnt->sr_data_direction = SCSI_DATA_READ;

        scsi_wait_req (SRpnt, (void *) scsi_cmd,
                  (void *) scsi_result,
                  256, SCSI_TIMEOUT+4*HZ, 3);

        SCSI_LOG_SCAN_BUS(3, printk("scsi: INQUIRY %s with code 0x%x\n",
                SRpnt->sr_result ? "failed" : "successful", SRpnt->sr_result));

        if (SRpnt->sr_result) {
                scsi_release_request(SRpnt);
                return 0;       /* assume no peripheral if any sort of error */
        }

        /*
         * Check the peripheral qualifier field - this tells us whether LUNS
         * are supported here or not.
         */
        if ((scsi_result[0] >> 5) == 3) {
                scsi_release_request(SRpnt);
                return 0;       /* assume no peripheral if any sort of error */
        }

        /*
         * Get any flags for this device.  
         */
        bflags = get_device_flags (scsi_result);


         /*   The Toshiba ROM was "gender-changed" here as an inline hack.
              This is now much more generic.
              This is a mess: What we really want is to leave the scsi_result
              alone, and just change the SDpnt structure. And the SDpnt is what
              we want print_inquiry to print.  -- REW
         */
        if (bflags & BLIST_ISDISK) {
                scsi_result[0] = TYPE_DISK;                                                
                scsi_result[1] |= 0x80;     /* removable */
        }

        if (bflags & BLIST_ISROM) {
                scsi_result[0] = TYPE_ROM;
                scsi_result[1] |= 0x80;     /* removable */
        }
    
        memcpy(SDpnt->vendor, scsi_result + 8, 8);
        memcpy(SDpnt->model, scsi_result + 16, 16);
        memcpy(SDpnt->rev, scsi_result + 32, 4);

        SDpnt->removable = (0x80 & scsi_result[1]) >> 7;
        /* Use the peripheral qualifier field to determine online/offline */
        if (((scsi_result[0] >> 5) & 7) == 1)   SDpnt->online = FALSE;
        else SDpnt->online = TRUE;
        SDpnt->lockable = SDpnt->removable;
        SDpnt->changed = 0;
        SDpnt->access_count = 0;
        SDpnt->busy = 0;
        SDpnt->has_cmdblocks = 0;
        /*
         * Currently, all sequential devices are assumed to be tapes, all random
         * devices disk, with the appropriate read only flags set for ROM / WORM
         * treated as RO.
         */
        switch (type = (scsi_result[0] & 0x1f)) {
        case TYPE_TAPE:
        case TYPE_DISK:
        case TYPE_MOD:
        case TYPE_PROCESSOR:
        case TYPE_SCANNER:
        case TYPE_MEDIUM_CHANGER:
        case TYPE_ENCLOSURE:
        case TYPE_COMM:
                SDpnt->writeable = 1;
                break;
        case TYPE_WORM:
        case TYPE_ROM:
                SDpnt->writeable = 0;
                break;
        default:
                printk("scsi: unknown type %d\n", type);
        }

        SDpnt->device_blocked = FALSE;
        SDpnt->device_busy = 0;
        SDpnt->single_lun = 0;
        SDpnt->soft_reset =
            (scsi_result[7] & 1) && ((scsi_result[3] & 7) == 2);
        SDpnt->random = (type == TYPE_TAPE) ? 0 : 1;
        SDpnt->type = (type & 0x1f);

        print_inquiry(scsi_result);

        sprintf (devname, "host%d/bus%d/target%d/lun%d",
                 SDpnt->host->host_no, SDpnt->channel, SDpnt->id, SDpnt->lun);
        if (SDpnt->de) printk ("DEBUG: dir: \"%s\" already exists\n", devname);
        else SDpnt->de = devfs_mk_dir (scsi_devfs_handle, devname, NULL);

        for (sdtpnt = scsi_devicelist; sdtpnt;
             sdtpnt = sdtpnt->next)
                if (sdtpnt->detect)
                        SDpnt->attached +=
                            (*sdtpnt->detect) (SDpnt);

        SDpnt->scsi_level = scsi_result[2] & 0x07;
        if (SDpnt->scsi_level >= 2 ||
            (SDpnt->scsi_level == 1 &&
             (scsi_result[3] & 0x0f) == 1))
                SDpnt->scsi_level++;

        /*
         * Accommodate drivers that want to sleep when they should be in a polling
         * loop.
         */
        SDpnt->disconnect = 0;


        /*
         * Set the tagged_queue flag for SCSI-II devices that purport to support
         * tagged queuing in the INQUIRY data.
         */
        SDpnt->tagged_queue = 0;
        if ((SDpnt->scsi_level >= SCSI_2) &&
            (scsi_result[7] & 2) &&
            !(bflags & BLIST_NOTQ)) {
                SDpnt->tagged_supported = 1;
                SDpnt->current_tag = 0;
        }
        /*
         * Some revisions of the Texel CD ROM drives have handshaking problems when
         * used with the Seagate controllers.  Before we know what type of device
         * we're talking to, we assume it's borken and then change it here if it
         * turns out that it isn't a TEXEL drive.
         */
        if ((bflags & BLIST_BORKEN) == 0)
                SDpnt->borken = 0;

        /*
         * If we want to only allow I/O to one of the luns attached to this device
         * at a time, then we set this flag.
         */
        if (bflags & BLIST_SINGLELUN)
                SDpnt->single_lun = 1;

        /*
         * These devices need this "key" to unlock the devices so we can use it
         */
        if ((bflags & BLIST_KEY) != 0) {
                printk("Unlocked floptical drive.\n");
                SDpnt->lockable = 0;
                scsi_cmd[0] = MODE_SENSE;
                scsi_cmd[1] = (lun << 5) & 0xe0;
                scsi_cmd[2] = 0x2e;
                scsi_cmd[3] = 0;
                scsi_cmd[4] = 0x2a;
                scsi_cmd[5] = 0;
                SRpnt->sr_cmd_len = 0;
                SRpnt->sr_data_direction = SCSI_DATA_READ;
                scsi_wait_req (SRpnt, (void *) scsi_cmd,
                        (void *) scsi_result, 0x2a,
                        SCSI_TIMEOUT, 3);
        }

        scsi_release_request(SRpnt);
        SRpnt = NULL;

        scsi_release_commandblocks(SDpnt);

        /*
         * This device was already hooked up to the host in question,
         * so at this point we just let go of it and it should be fine.  We do need to
         * allocate a new one and attach it to the host so that we can further scan the bus.
         */
        SDpnt = (Scsi_Device *) kmalloc(sizeof(Scsi_Device), GFP_ATOMIC);
        if (!SDpnt) {
                printk("scsi: scan_scsis_single: Cannot malloc\n");
                return 0;
        }
        memset(SDpnt, 0, sizeof(Scsi_Device));

        *SDpnt2 = SDpnt;
        SDpnt->queue_depth = 1;
        SDpnt->host = shpnt;
        SDpnt->online = TRUE;

        /*
         * Register the queue for the device.  All I/O requests will come
         * in through here.  We also need to register a pointer to
         * ourselves, since the queue handler won't know what device
         * the queue actually represents.   We could look it up, but it
         * is pointless work.
         */
        scsi_initialize_queue(SDpnt, shpnt);
        SDpnt->host = shpnt;
        initialize_merge_fn(SDpnt);

        /*
         * Mark this device as online, or otherwise we won't be able to do much with it.
         */
        SDpnt->online = TRUE;

        /*
         * Initialize the object that we will use to wait for command blocks.
         */
        init_waitqueue_head(&SDpnt->scpnt_wait);

        /*
         * Since we just found one device, there had damn well better be one in the list
         * already.
         */
        if (shpnt->host_queue == NULL)
                panic("scan_scsis_single: Host queue == NULL\n");

        SDtail = shpnt->host_queue;
        while (SDtail->next) {
                SDtail = SDtail->next;
        }

        /* Add this device to the linked list at the end */
        SDtail->next = SDpnt;
        SDpnt->prev = SDtail;
        SDpnt->next = NULL;

        /*
         * Some scsi devices cannot be polled for lun != 0 due to firmware bugs
         */
        if (bflags & BLIST_NOLUN)
                return 0;       /* break; */

        /*
         * If this device is known to support sparse multiple units, override the
         * other settings, and scan all of them.
         */
        if (bflags & BLIST_SPARSELUN) {
                *max_dev_lun = 8;
                *sparse_lun = 1;
                return 1;
        }
        /*
         * If this device is known to support multiple units, override the other
         * settings, and scan all of them.
         */
        if (bflags & BLIST_FORCELUN) {
                *max_dev_lun = 8;
                return 1;
        }
        /*
         * REGAL CDC-4X: avoid hang after LUN 4
         */
        if (bflags & BLIST_MAX5LUN) {
                *max_dev_lun = 5;
                return 1;
        }

        /*
         * We assume the device can't handle lun!=0 if: - it reports scsi-0
         * (ANSI SCSI Revision 0) (old drives like MAXTOR XT-3280) or - it
         * reports scsi-1 (ANSI SCSI Revision 1) and Response Data Format 0
         */
        if (((scsi_result[2] & 0x07) == 0)
            ||
            ((scsi_result[2] & 0x07) == 1 &&
             (scsi_result[3] & 0x0f) == 0))
                return 0;
        return 1;
}